Transfer tables



R. H. BERGSTRAND TRANSFER TABLES Nov. 20, 1956 Filed Feb. 12, 1954- IIIII'IIII brlLfll RICHARD H BERG'STRA/VD BY AM. C1142,

Filed Feb. 12, 1954 2 Sheets-Sheet 2 i uvmvmz RICHA R0 H. BERGSTRA/VD United States Patent TRANSFER TABLES Richard H. Bergstrand, Moline, Ill., assignor to The gllgnline Tool Company, Moline, 111., a'corporation of Application February 12, 1954, Serial No. 409,826

6 Claims. (Cl. 198-19) The invention relates to that type of transfer table which is provided with means to move an object horizontally along the surface of the table. Each movement carries the object forward along the table the same distance. Such transfer tables are used to move a work piecegenerally a casting-from one machine to another. Each machine performs a different operation on the same casting. By way of example, a motor block casting may be placed on one end of the transfer table and is first moved into a position where a machine will perform the initial operation on the casting. After the lapse of an appropriate time, the casting is again moved forward to the next position where another machine operates on it while a second casting that has in the interim been placed on the end of the table is moved into position before the first machine. There may be any number of machines in the row-each performing a different operation on the same casting as it travels along the transfer table.

The work pieces need not be castings, but as they generally are castings, the term casting will be used to cover any type of work piece. The castings are usually first machined on one surface and one or more holes which are to be used for alignment are drilled. 'Dhus each casting rests on its machined surface securely supported against tilting, and when the casting is in front of a machine, dowel pins pass into the drilled holes to precisely locate the casting before the machine. Frequently a clamp is provided which will, after the casting has been located in its precise position, hold the casting rigidly in position while the machine is working on it.

The invention permits faster operation and increased output, by reducing the time required to move the casting from one position on the table to the next position. This is made possible by moving the castings forward rapidly and positively grasping the casting during this movement both to impel it forward and to prevent overtravel. The necessity of bringing a casting that has overshot the desired location back to its proper position is thus eliminated.

It will be obvious that where a number of expensive machine tools are lined up along a transfer table, this is important because any mishap that will cause any one of the castings to travel too far and thus prevent the dowel pin finding its hole will tie up the whole line, ruin work pieces, and perhaps break cutters.

Moving the castings rapidly from one position to the next necessarily means accelerating the speed of the casting which builds up kinetic energy and if the casting is merely pushed, one or another casting may continue to move due to inertia beyond the end of the travel of the pawl that is pushing the casting.

The object of the invention is to provide a transfer table having means for moving castings from one position to another which both push the casting and prevent its overtravel.

The invention contemplates a novel device which, when moved in one direction will cause two fingers to take hold of opposite sides of a casting or flange and move it for- 2,771,172 Patented Nov. 20, 1956 ward and when moved in the other direction leave the casting in the new position to which it has been moved.

The invention contemplates two parallel bars, one carrying pawls, the other determining the angular position of at least one of these pawls. The two bars generally travel together but are in a different relative position when a driving unit moves them in one direction than when the driving unit is moving them in the opposite direction.

Figure 1 is in plan view partly in section of a transfer table serving a plurality of stations at each of which machine tools, not shown, are adapted to work on the casting at some stations.

Figure 2 shows the transfer table in elevation, partly in section, passing a plurality of stations at each of which a machine tool is adapted to work on the casting.

Figure 3 shows the transfer table in vertical cross section, taken along lines 33 in Figure 1.

Figure 4, drawn to a larger scale, shows in plan view the device that moves the castings in the position the device occupies when it is moving the castings forward.

Figure 5 shows the same parts in the position they assume when the device is moving backward and is dis engaged from the castings.

In these drawings, a machine tool station is generally indicated at l and another at 2. Each of these stations may consist of a base 4 having a hood 5 carrying a clamping .device 6 which may be hydraulically operated and which presses the work piece 10 down on its support.

The hood 5 may have opening 7 permitting machine tools to reach the work piece. The work piece may rest and slide on tracks 11.

These tracks extend beyond the bases 4 to supports 12. Means are provided for the precise location of the work piece at each station such as the vertically movable dowel pins 13. Where the casting forms an internal combustion engine block or the like, the portion supporting the shaft in an assembled motor block may be machined first and a guide rail 14 provided that extends up into thismachined portion of the casting.

The work piece to be machined is placed on the extension of the table with the semi-circular machined portion aligned on guide rail 14. Thus the guided movement of the piece in a straight line is assured. The movement in a straight line can also be assured in any other manner.

The casting is moved by a sliding bar 17 that can be moved backward and forward by a cylinder 18 or in some other manner.

If the bar 17 is moved by a cylinder, the cylinder may be supported on the work station base 4 and the piston rod 20 may be firmly connected to a cross bar 21.

This cross bar 21 slides freely on two shafts 22 extending from the support 12 to the base 4 of the station. The square bar 17 has a hole drilled into its end and a stud 23 is anchored therein by a pin 24. This stud 23 extends through a hole 25 in the cross bar 21 and allows motion of the bar 17 relative to the cross piece 21. The stud 23 carries a nut 26 and a lock nut 27 which permits regulating the movement of bar 17 relative to the cross piece 21. It will be obvious that if the piston 20 moves in the direction 28 the parts will be in the position shown in Figure 5 and nut 26 will be hearing against the cross piece 21.

However, if the piston is moving in the opposite direction, the parts will be in the position shown in Figure 4 and the end of the bar 17 will be bearing against the cross piece 21.

The casting may have a flange 30 which the pawls carried by the bar 17 may engage. The bar engages the flange by the two pawls 31, 32. If the casting does not have a convenient flange 30, one pawl may engage the front end of the casting or work piece and the other pawl its other end. The pawl 31 is supported in such a way that it may not move clockwise from the position shown in Figure 4 but may move in the other direction against a compression spring 33. The pawl may be supported by a pin 34 in a recess 35 in bar 17. In Figure 4 the pawl is bearing against the edge 36 of the recess. It will be obvious that when the bar is moving in the direction shown by arrow 28 in Figure the pawl 31 can pass the flange on the casting without moving it, but when moving in the opposite direction, as shown in Figure 4, it will push the casting along the tracks 11.

The bar 17 is also recessed at 40 and a pin 41 carries a second pawl 32.

This pawl has an extension 42 ending in a circular head 43. It is obvious that the angular position of pawl 32 can be changed by moving the head 43 relative to the bar 17.

This is accomplished by providing another bar 44 parallel to bar 17 and firmly attached to the cross piece 21 at 45. The bar 44 carries a recess 46 whose sides 47, 48 engage head 43.

In the operation of the invention, it will be assumed a casting is in position 38 being machined, and that an additional casting has just been placed on the tracks in position 37.

When the machine tools operating on the castings in positions 38 have had time to finish, the operation on that casting, the piston rod 20 moves in the direction 28 and the parts are in the position shown in Figure 5. The pawl 32. is drawn clear of the casting and the pawl 31 can ride over the casting flange compressing the spring 33. When the piston rod 20 has reached the end of its travel and starts back in the reverse direction, the rod 44 starts to move back immediately while the rod 17 rests. Thus the pawl 32 is turned to the position shown in Figure 4 and if the nut 26 has been set properly, the two pawls 31 and 32 will bear against the flange 30 simultaneously.

The casting cannot overshoot because it would press against pawl 32 whose position angularly is determined by the stroke of the cylinder.

I claim:

1. In power actuated mechanism adapted to transfer pieces from one position to another by a reciprocating member at high speed while preventing the moving piece from travelling beyond the range of the reciprocating member, in combination, a support at each of several stations for one of a plurality of duplicate pieces, a guiding element extending over all the supports and engaging all of the pieces in a manner to assure the movement of all pieces along the same path, a bar axially movable parallel to said path, power means adapted to rapidly move said bar through a fixed distance in either direction, devices carried by said bar that are adapted to engage each of said pieces on opposite sides, automatic means which will cause said devices to engage each of said pieces when moving in one direction and bringing the pieces to rest when the bar reaches the end of its travel and disengaging from said pieces when the bar moves in the opposite direction.

2. In power actuated mechanism adapted to transfer pieces from one position to another by a reciprocating member at high speed while preventing the moving piece from travelling beyond the range of the reciprocating member, in combination, a plurality of work stations each adapted to support a pi ce, a supporting surface leading to the first of said work stations, supporting surfaces connectin g said work stations, a guide engaging all the pieces and extending along the entire path of the pieces to assure the movement of all the pieces along the same path, a horizontally movable bar, means carried by said bar adapted to engage each piece both on the front and the back, automatic means which will cause said devices to engage all the pieces when the bar is moving in one direc tion and hold them until the bar stops but which will cause the devices to release the pieces when the bar moves in the opposite direction, power means adapted to move the bar a fixed axial distance in either direction to move the pieces the exact distance from one work position to another.

3. In power actuated mechanism adapted to transfer pieces from one position to another by a reciprocating member at high speed while preventing the moving piece from travelling beyond the range of the reciprocating member, in combination, a plurality of work stations each adapted to support a piece, a supporting surface leading to the first of said work stations, supporting surfaces connecting said work stations, a guide engaging all the pieces and extending along the entire path of the pieces to assure the movement of all the pieces along the same path, a horizontally movable bar, a power cylinder whose piston will either move the bar a fixed distance in one direction or in the other direction and come to rest at the end of each movement, means carried by said bar adapted to attach each piece to said bar, automatic means which will cause said devices to attach the bar to the pieces when the bar is moving and until it comes to rest in one direction but which will cause the devices to free the bar from the pieces when the bar moves in the opposite direction.

4. A device for moving a piece along a transfer table a number of successive equal steps, comprising, a cylinder adapted to move a piston rod in either direction over a fixed path, a cross piece connected to said piston rod, guide rods along which said cross piece is adapted to slide, a bar adapted to be moved axially by said cross piece, a pair of pawls carried by said bar for each piece to be engaged, means causing said pawls to engage the .piece both in front and inthe back when the piston rod moves in one direction and holding the engagement when the bar comes to rest, means to disengage said pawls from the piece when the piston moves in the other direction.

5. A device for moving pieces along a transfer table in a number of successive equal steps, comprising, a cylinder adapted to move a piston rod in either direction over a fixed path, a cross piece connected to said piston rod, guide rods along which said cross piece is adapted to slide, a bar adapted to be moved axially by said cross piece, a pair of pawls carried by said rod for each piece to be engaged, a second bar parallel to said rod adapted to cause said pawls to engage the pieces when the piston rod moves in one direction and holding the engagement when the first bar comes to rest, and to move relative to said first named bar to disengage said pawls from the pieces when the piston moves in the other direction.

6. A device for moving a piece along a transfer table a number of successive equal steps, comprising, a cylinder adapted to move a piston rod in either direction over a fixed path, a cross piece connected to said piston rod, guide rods along which said cross piece is adapted to slide, a bar adapted to be moved axially by said cross piece, a pair of pawls carried by said rod for each piece to be engaged, a second bar moving alongside said first named rod, means on said second rod engaging one of said pawls, means for attaching said second bar directly to the cross piece, means connecting said first named bar to the cross piece in a manner to allow limited movement of the first and the second rod to each other as the direction of movement of the cross piece is reversed.

References Cited in the file of this patent UNITED STATES PATENTS 1,934,325 Peterson Nov. 7, 1933 

